From 97d3ac75e5e0ebf7ca38ae74cebd201c09b97ab2 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Sun, 24 Apr 2011 19:06:16 +0000 Subject: xfs: exact busy extent tracking Update the extent tree in case we have to reuse a busy extent, so that it always is kept uptodate. This is done by replacing the busy list searches with a new xfs_alloc_busy_reuse helper, which updates the busy extent tree in case of a reuse. This allows us to allow reusing metadata extents unconditionally, and thus avoid log forces especially for allocation btree blocks. Signed-off-by: Christoph Hellwig Signed-off-by: Alex Elder --- fs/xfs/linux-2.6/xfs_trace.h | 79 ++------- fs/xfs/xfs_ag.h | 1 - fs/xfs/xfs_alloc.c | 373 +++++++++++++++++++++++++------------------ fs/xfs/xfs_alloc.h | 4 + fs/xfs/xfs_alloc_btree.c | 15 +- fs/xfs/xfs_log.c | 7 - fs/xfs/xfs_log.h | 2 - fs/xfs/xfs_log_priv.h | 2 + fs/xfs/xfs_types.h | 2 - 9 files changed, 237 insertions(+), 248 deletions(-) (limited to 'fs/xfs') diff --git a/fs/xfs/linux-2.6/xfs_trace.h b/fs/xfs/linux-2.6/xfs_trace.h index e5252c4d95c9..37df9ad7fd1a 100644 --- a/fs/xfs/linux-2.6/xfs_trace.h +++ b/fs/xfs/linux-2.6/xfs_trace.h @@ -1151,44 +1151,7 @@ TRACE_EVENT(xfs_bunmap, ); -#define XFS_BUSY_SYNC \ - { 0, "async" }, \ - { 1, "sync" } - -TRACE_EVENT(xfs_alloc_busy, - TP_PROTO(struct xfs_trans *trans, xfs_agnumber_t agno, - xfs_agblock_t agbno, xfs_extlen_t len, int sync), - TP_ARGS(trans, agno, agbno, len, sync), - TP_STRUCT__entry( - __field(dev_t, dev) - __field(struct xfs_trans *, tp) - __field(int, tid) - __field(xfs_agnumber_t, agno) - __field(xfs_agblock_t, agbno) - __field(xfs_extlen_t, len) - __field(int, sync) - ), - TP_fast_assign( - __entry->dev = trans->t_mountp->m_super->s_dev; - __entry->tp = trans; - __entry->tid = trans->t_ticket->t_tid; - __entry->agno = agno; - __entry->agbno = agbno; - __entry->len = len; - __entry->sync = sync; - ), - TP_printk("dev %d:%d trans 0x%p tid 0x%x agno %u agbno %u len %u %s", - MAJOR(__entry->dev), MINOR(__entry->dev), - __entry->tp, - __entry->tid, - __entry->agno, - __entry->agbno, - __entry->len, - __print_symbolic(__entry->sync, XFS_BUSY_SYNC)) - -); - -TRACE_EVENT(xfs_alloc_unbusy, +DECLARE_EVENT_CLASS(xfs_busy_class, TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno, xfs_agblock_t agbno, xfs_extlen_t len), TP_ARGS(mp, agno, agbno, len), @@ -1210,36 +1173,16 @@ TRACE_EVENT(xfs_alloc_unbusy, __entry->agbno, __entry->len) ); - -#define XFS_BUSY_STATES \ - { 0, "missing" }, \ - { 1, "found" } - -TRACE_EVENT(xfs_alloc_busysearch, - TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno, - xfs_agblock_t agbno, xfs_extlen_t len, int found), - TP_ARGS(mp, agno, agbno, len, found), - TP_STRUCT__entry( - __field(dev_t, dev) - __field(xfs_agnumber_t, agno) - __field(xfs_agblock_t, agbno) - __field(xfs_extlen_t, len) - __field(int, found) - ), - TP_fast_assign( - __entry->dev = mp->m_super->s_dev; - __entry->agno = agno; - __entry->agbno = agbno; - __entry->len = len; - __entry->found = found; - ), - TP_printk("dev %d:%d agno %u agbno %u len %u %s", - MAJOR(__entry->dev), MINOR(__entry->dev), - __entry->agno, - __entry->agbno, - __entry->len, - __print_symbolic(__entry->found, XFS_BUSY_STATES)) -); +#define DEFINE_BUSY_EVENT(name) \ +DEFINE_EVENT(xfs_busy_class, name, \ + TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno, \ + xfs_agblock_t agbno, xfs_extlen_t len), \ + TP_ARGS(mp, agno, agbno, len)) +DEFINE_BUSY_EVENT(xfs_alloc_busy); +DEFINE_BUSY_EVENT(xfs_alloc_busy_enomem); +DEFINE_BUSY_EVENT(xfs_alloc_busy_force); +DEFINE_BUSY_EVENT(xfs_alloc_busy_reuse); +DEFINE_BUSY_EVENT(xfs_alloc_busy_clear); TRACE_EVENT(xfs_alloc_busy_trim, TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno, diff --git a/fs/xfs/xfs_ag.h b/fs/xfs/xfs_ag.h index 58632cc17f2d..da0a561ffba2 100644 --- a/fs/xfs/xfs_ag.h +++ b/fs/xfs/xfs_ag.h @@ -187,7 +187,6 @@ struct xfs_busy_extent { xfs_agnumber_t agno; xfs_agblock_t bno; xfs_extlen_t length; - xlog_tid_t tid; /* transaction that created this */ }; /* diff --git a/fs/xfs/xfs_alloc.c b/fs/xfs/xfs_alloc.c index ff54ef428348..53157d4d5e8b 100644 --- a/fs/xfs/xfs_alloc.c +++ b/fs/xfs/xfs_alloc.c @@ -1396,8 +1396,9 @@ xfs_alloc_ag_vextent_small( if (error) goto error0; if (fbno != NULLAGBLOCK) { - if (xfs_alloc_busy_search(args->mp, args->agno, fbno, 1)) - xfs_trans_set_sync(args->tp); + xfs_alloc_busy_reuse(args->mp, args->agno, fbno, 1, + args->userdata); + if (args->userdata) { xfs_buf_t *bp; @@ -2475,100 +2476,6 @@ error0: return error; } - -/* - * AG Busy list management - * The busy list contains block ranges that have been freed but whose - * transactions have not yet hit disk. If any block listed in a busy - * list is reused, the transaction that freed it must be forced to disk - * before continuing to use the block. - * - * xfs_alloc_busy_insert - add to the per-ag busy list - * xfs_alloc_busy_clear - remove an item from the per-ag busy list - * xfs_alloc_busy_search - search for a busy extent - */ - -/* - * Insert a new extent into the busy tree. - * - * The busy extent tree is indexed by the start block of the busy extent. - * there can be multiple overlapping ranges in the busy extent tree but only - * ever one entry at a given start block. The reason for this is that - * multi-block extents can be freed, then smaller chunks of that extent - * allocated and freed again before the first transaction commit is on disk. - * If the exact same start block is freed a second time, we have to wait for - * that busy extent to pass out of the tree before the new extent is inserted. - * There are two main cases we have to handle here. - * - * The first case is a transaction that triggers a "free - allocate - free" - * cycle. This can occur during btree manipulations as a btree block is freed - * to the freelist, then allocated from the free list, then freed again. In - * this case, the second extxpnet free is what triggers the duplicate and as - * such the transaction IDs should match. Because the extent was allocated in - * this transaction, the transaction must be marked as synchronous. This is - * true for all cases where the free/alloc/free occurs in the one transaction, - * hence the addition of the ASSERT(tp->t_flags & XFS_TRANS_SYNC) to this case. - * This serves to catch violations of the second case quite effectively. - * - * The second case is where the free/alloc/free occur in different - * transactions. In this case, the thread freeing the extent the second time - * can't mark the extent busy immediately because it is already tracked in a - * transaction that may be committing. When the log commit for the existing - * busy extent completes, the busy extent will be removed from the tree. If we - * allow the second busy insert to continue using that busy extent structure, - * it can be freed before this transaction is safely in the log. Hence our - * only option in this case is to force the log to remove the existing busy - * extent from the list before we insert the new one with the current - * transaction ID. - * - * The problem we are trying to avoid in the free-alloc-free in separate - * transactions is most easily described with a timeline: - * - * Thread 1 Thread 2 Thread 3 xfslogd - * xact alloc - * free X - * mark busy - * commit xact - * free xact - * xact alloc - * alloc X - * busy search - * mark xact sync - * commit xact - * free xact - * force log - * checkpoint starts - * .... - * xact alloc - * free X - * mark busy - * finds match - * *** KABOOM! *** - * .... - * log IO completes - * unbusy X - * checkpoint completes - * - * By issuing a log force in thread 3 @ "KABOOM", the thread will block until - * the checkpoint completes, and the busy extent it matched will have been - * removed from the tree when it is woken. Hence it can then continue safely. - * - * However, to ensure this matching process is robust, we need to use the - * transaction ID for identifying transaction, as delayed logging results in - * the busy extent and transaction lifecycles being different. i.e. the busy - * extent is active for a lot longer than the transaction. Hence the - * transaction structure can be freed and reallocated, then mark the same - * extent busy again in the new transaction. In this case the new transaction - * will have a different tid but can have the same address, and hence we need - * to check against the tid. - * - * Future: for delayed logging, we could avoid the log force if the extent was - * first freed in the current checkpoint sequence. This, however, requires the - * ability to pin the current checkpoint in memory until this transaction - * commits to ensure that both the original free and the current one combine - * logically into the one checkpoint. If the checkpoint sequences are - * different, however, we still need to wait on a log force. - */ void xfs_alloc_busy_insert( struct xfs_trans *tp, @@ -2580,9 +2487,7 @@ xfs_alloc_busy_insert( struct xfs_busy_extent *busyp; struct xfs_perag *pag; struct rb_node **rbp; - struct rb_node *parent; - int match; - + struct rb_node *parent = NULL; new = kmem_zalloc(sizeof(struct xfs_busy_extent), KM_MAYFAIL); if (!new) { @@ -2591,7 +2496,7 @@ xfs_alloc_busy_insert( * block, make this a synchronous transaction to insure that * the block is not reused before this transaction commits. */ - trace_xfs_alloc_busy(tp, agno, bno, len, 1); + trace_xfs_alloc_busy_enomem(tp->t_mountp, agno, bno, len); xfs_trans_set_sync(tp); return; } @@ -2599,66 +2504,28 @@ xfs_alloc_busy_insert( new->agno = agno; new->bno = bno; new->length = len; - new->tid = xfs_log_get_trans_ident(tp); - INIT_LIST_HEAD(&new->list); /* trace before insert to be able to see failed inserts */ - trace_xfs_alloc_busy(tp, agno, bno, len, 0); + trace_xfs_alloc_busy(tp->t_mountp, agno, bno, len); pag = xfs_perag_get(tp->t_mountp, new->agno); -restart: spin_lock(&pag->pagb_lock); rbp = &pag->pagb_tree.rb_node; - parent = NULL; - busyp = NULL; - match = 0; - while (*rbp && match >= 0) { + while (*rbp) { parent = *rbp; busyp = rb_entry(parent, struct xfs_busy_extent, rb_node); if (new->bno < busyp->bno) { - /* may overlap, but exact start block is lower */ rbp = &(*rbp)->rb_left; - if (new->bno + new->length > busyp->bno) - match = busyp->tid == new->tid ? 1 : -1; + ASSERT(new->bno + new->length <= busyp->bno); } else if (new->bno > busyp->bno) { - /* may overlap, but exact start block is higher */ rbp = &(*rbp)->rb_right; - if (bno < busyp->bno + busyp->length) - match = busyp->tid == new->tid ? 1 : -1; + ASSERT(bno >= busyp->bno + busyp->length); } else { - match = busyp->tid == new->tid ? 1 : -1; - break; + ASSERT(0); } } - if (match < 0) { - /* overlap marked busy in different transaction */ - spin_unlock(&pag->pagb_lock); - xfs_log_force(tp->t_mountp, XFS_LOG_SYNC); - goto restart; - } - if (match > 0) { - /* - * overlap marked busy in same transaction. Update if exact - * start block match, otherwise combine the busy extents into - * a single range. - */ - if (busyp->bno == new->bno) { - busyp->length = max(busyp->length, new->length); - spin_unlock(&pag->pagb_lock); - ASSERT(tp->t_flags & XFS_TRANS_SYNC); - xfs_perag_put(pag); - kmem_free(new); - return; - } - rb_erase(&busyp->rb_node, &pag->pagb_tree); - new->length = max(busyp->bno + busyp->length, - new->bno + new->length) - - min(busyp->bno, new->bno); - new->bno = min(busyp->bno, new->bno); - } else - busyp = NULL; rb_link_node(&new->rb_node, parent, rbp); rb_insert_color(&new->rb_node, &pag->pagb_tree); @@ -2666,7 +2533,6 @@ restart: list_add(&new->list, &tp->t_busy); spin_unlock(&pag->pagb_lock); xfs_perag_put(pag); - kmem_free(busyp); } /* @@ -2715,11 +2581,195 @@ xfs_alloc_busy_search( } } spin_unlock(&pag->pagb_lock); - trace_xfs_alloc_busysearch(mp, agno, bno, len, !!match); xfs_perag_put(pag); return match; } +/* + * The found free extent [fbno, fend] overlaps part or all of the given busy + * extent. If the overlap covers the beginning, the end, or all of the busy + * extent, the overlapping portion can be made unbusy and used for the + * allocation. We can't split a busy extent because we can't modify a + * transaction/CIL context busy list, but we can update an entries block + * number or length. + * + * Returns true if the extent can safely be reused, or false if the search + * needs to be restarted. + */ +STATIC bool +xfs_alloc_busy_update_extent( + struct xfs_mount *mp, + struct xfs_perag *pag, + struct xfs_busy_extent *busyp, + xfs_agblock_t fbno, + xfs_extlen_t flen, + bool userdata) +{ + xfs_agblock_t fend = fbno + flen; + xfs_agblock_t bbno = busyp->bno; + xfs_agblock_t bend = bbno + busyp->length; + + /* + * If there is a busy extent overlapping a user allocation, we have + * no choice but to force the log and retry the search. + * + * Fortunately this does not happen during normal operation, but + * only if the filesystem is very low on space and has to dip into + * the AGFL for normal allocations. + */ + if (userdata) + goto out_force_log; + + if (bbno < fbno && bend > fend) { + /* + * Case 1: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +---------+ + * fbno fend + */ + + /* + * We would have to split the busy extent to be able to track + * it correct, which we cannot do because we would have to + * modify the list of busy extents attached to the transaction + * or CIL context, which is immutable. + * + * Force out the log to clear the busy extent and retry the + * search. + */ + goto out_force_log; + } else if (bbno >= fbno && bend <= fend) { + /* + * Case 2: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +-----------------+ + * fbno fend + * + * Case 3: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +--------------------------+ + * fbno fend + * + * Case 4: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +--------------------------+ + * fbno fend + * + * Case 5: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +-----------------------------------+ + * fbno fend + * + */ + + /* + * The busy extent is fully covered by the extent we are + * allocating, and can simply be removed from the rbtree. + * However we cannot remove it from the immutable list + * tracking busy extents in the transaction or CIL context, + * so set the length to zero to mark it invalid. + * + * We also need to restart the busy extent search from the + * tree root, because erasing the node can rearrange the + * tree topology. + */ + rb_erase(&busyp->rb_node, &pag->pagb_tree); + busyp->length = 0; + return false; + } else if (fend < bend) { + /* + * Case 6: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +---------+ + * fbno fend + * + * Case 7: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +------------------+ + * fbno fend + * + */ + busyp->bno = fend; + } else if (bbno < fbno) { + /* + * Case 8: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +-------------+ + * fbno fend + * + * Case 9: + * bbno bend + * +BBBBBBBBBBBBBBBBB+ + * +----------------------+ + * fbno fend + */ + busyp->length = fbno - busyp->bno; + } else { + ASSERT(0); + } + + trace_xfs_alloc_busy_reuse(mp, pag->pag_agno, fbno, flen); + return true; + +out_force_log: + spin_unlock(&pag->pagb_lock); + xfs_log_force(mp, XFS_LOG_SYNC); + trace_xfs_alloc_busy_force(mp, pag->pag_agno, fbno, flen); + spin_lock(&pag->pagb_lock); + return false; +} + + +/* + * For a given extent [fbno, flen], make sure we can reuse it safely. + */ +void +xfs_alloc_busy_reuse( + struct xfs_mount *mp, + xfs_agnumber_t agno, + xfs_agblock_t fbno, + xfs_extlen_t flen, + bool userdata) +{ + struct xfs_perag *pag; + struct rb_node *rbp; + + ASSERT(flen > 0); + + pag = xfs_perag_get(mp, agno); + spin_lock(&pag->pagb_lock); +restart: + rbp = pag->pagb_tree.rb_node; + while (rbp) { + struct xfs_busy_extent *busyp = + rb_entry(rbp, struct xfs_busy_extent, rb_node); + xfs_agblock_t bbno = busyp->bno; + xfs_agblock_t bend = bbno + busyp->length; + + if (fbno + flen <= bbno) { + rbp = rbp->rb_left; + continue; + } else if (fbno >= bend) { + rbp = rbp->rb_right; + continue; + } + + if (!xfs_alloc_busy_update_extent(mp, pag, busyp, fbno, flen, + userdata)) + goto restart; + } + spin_unlock(&pag->pagb_lock); + xfs_perag_put(pag); +} + /* * For a given extent [fbno, flen], search the busy extent list to find a * subset of the extent that is not busy. If *rlen is smaller than @@ -2734,13 +2784,16 @@ xfs_alloc_busy_trim( xfs_agblock_t *rbno, xfs_extlen_t *rlen) { - xfs_agblock_t fbno = bno; - xfs_extlen_t flen = len; + xfs_agblock_t fbno; + xfs_extlen_t flen; struct rb_node *rbp; - ASSERT(flen > 0); + ASSERT(len > 0); spin_lock(&args->pag->pagb_lock); +restart: + fbno = bno; + flen = len; rbp = args->pag->pagb_tree.rb_node; while (rbp && flen >= args->minlen) { struct xfs_busy_extent *busyp = @@ -2757,6 +2810,18 @@ xfs_alloc_busy_trim( continue; } + /* + * If this is a metadata allocation, try to reuse the busy + * extent instead of trimming the allocation. + */ + if (!args->userdata) { + if (!xfs_alloc_busy_update_extent(args->mp, args->pag, + busyp, fbno, flen, + false)) + goto restart; + continue; + } + if (bbno <= fbno) { /* start overlap */ @@ -2906,17 +2971,15 @@ xfs_alloc_busy_clear( { struct xfs_perag *pag; - trace_xfs_alloc_unbusy(mp, busyp->agno, busyp->bno, - busyp->length); - - ASSERT(xfs_alloc_busy_search(mp, busyp->agno, busyp->bno, - busyp->length) == 1); - list_del_init(&busyp->list); pag = xfs_perag_get(mp, busyp->agno); spin_lock(&pag->pagb_lock); - rb_erase(&busyp->rb_node, &pag->pagb_tree); + if (busyp->length) { + trace_xfs_alloc_busy_clear(mp, busyp->agno, busyp->bno, + busyp->length); + rb_erase(&busyp->rb_node, &pag->pagb_tree); + } spin_unlock(&pag->pagb_lock); xfs_perag_put(pag); diff --git a/fs/xfs/xfs_alloc.h b/fs/xfs/xfs_alloc.h index d0b3bc72005b..de5e27c95170 100644 --- a/fs/xfs/xfs_alloc.h +++ b/fs/xfs/xfs_alloc.h @@ -145,6 +145,10 @@ xfs_alloc_busy_clear(struct xfs_mount *mp, struct xfs_busy_extent *busyp); int xfs_alloc_busy_search(struct xfs_mount *mp, xfs_agnumber_t agno, xfs_agblock_t bno, xfs_extlen_t len); + +void +xfs_alloc_busy_reuse(struct xfs_mount *mp, xfs_agnumber_t agno, + xfs_agblock_t fbno, xfs_extlen_t flen, bool userdata); #endif /* __KERNEL__ */ /* diff --git a/fs/xfs/xfs_alloc_btree.c b/fs/xfs/xfs_alloc_btree.c index bcfe92f47edd..8b469d53599f 100644 --- a/fs/xfs/xfs_alloc_btree.c +++ b/fs/xfs/xfs_alloc_btree.c @@ -94,8 +94,8 @@ xfs_allocbt_alloc_block( *stat = 0; return 0; } - if (xfs_alloc_busy_search(cur->bc_mp, cur->bc_private.a.agno, bno, 1)) - xfs_trans_set_sync(cur->bc_tp); + + xfs_alloc_busy_reuse(cur->bc_mp, cur->bc_private.a.agno, bno, 1, false); xfs_trans_agbtree_delta(cur->bc_tp, 1); new->s = cpu_to_be32(bno); @@ -120,17 +120,6 @@ xfs_allocbt_free_block( if (error) return error; - /* - * Since blocks move to the free list without the coordination used in - * xfs_bmap_finish, we can't allow block to be available for - * reallocation and non-transaction writing (user data) until we know - * that the transaction that moved it to the free list is permanently - * on disk. We track the blocks by declaring these blocks as "busy"; - * the busy list is maintained on a per-ag basis and each transaction - * records which entries should be removed when the iclog commits to - * disk. If a busy block is allocated, the iclog is pushed up to the - * LSN that freed the block. - */ xfs_alloc_busy_insert(cur->bc_tp, be32_to_cpu(agf->agf_seqno), bno, 1); xfs_trans_agbtree_delta(cur->bc_tp, -1); return 0; diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c index b612ce4520ae..18fd4beffcc3 100644 --- a/fs/xfs/xfs_log.c +++ b/fs/xfs/xfs_log.c @@ -3248,13 +3248,6 @@ xfs_log_ticket_get( return ticket; } -xlog_tid_t -xfs_log_get_trans_ident( - struct xfs_trans *tp) -{ - return tp->t_ticket->t_tid; -} - /* * Allocate and initialise a new log ticket. */ diff --git a/fs/xfs/xfs_log.h b/fs/xfs/xfs_log.h index 3bd3291ef8d2..78c9039994af 100644 --- a/fs/xfs/xfs_log.h +++ b/fs/xfs/xfs_log.h @@ -189,8 +189,6 @@ void xlog_iodone(struct xfs_buf *); struct xlog_ticket *xfs_log_ticket_get(struct xlog_ticket *ticket); void xfs_log_ticket_put(struct xlog_ticket *ticket); -xlog_tid_t xfs_log_get_trans_ident(struct xfs_trans *tp); - void xfs_log_commit_cil(struct xfs_mount *mp, struct xfs_trans *tp, struct xfs_log_vec *log_vector, xfs_lsn_t *commit_lsn, int flags); diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h index 5864850e9e34..2d3b6a498d63 100644 --- a/fs/xfs/xfs_log_priv.h +++ b/fs/xfs/xfs_log_priv.h @@ -146,6 +146,8 @@ static inline uint xlog_get_client_id(__be32 i) shutdown */ #define XLOG_TAIL_WARN 0x10 /* log tail verify warning issued */ +typedef __uint32_t xlog_tid_t; + #ifdef __KERNEL__ /* * Below are states for covering allocation transactions. diff --git a/fs/xfs/xfs_types.h b/fs/xfs/xfs_types.h index 26d1867d8156..65584b55607d 100644 --- a/fs/xfs/xfs_types.h +++ b/fs/xfs/xfs_types.h @@ -73,8 +73,6 @@ typedef __int32_t xfs_tid_t; /* transaction identifier */ typedef __uint32_t xfs_dablk_t; /* dir/attr block number (in file) */ typedef __uint32_t xfs_dahash_t; /* dir/attr hash value */ -typedef __uint32_t xlog_tid_t; /* transaction ID type */ - /* * These types are 64 bits on disk but are either 32 or 64 bits in memory. * Disk based types: -- cgit v1.2.3-59-g8ed1b